Sepulveda, E., Mangalaraja, R. V., Udayabhaskar, R., Cobo, R., Berzal, M. E., Jimenez, J., et al. (2022). Preparation of LSGM electrolyte via fast combustion method and analysis of electrical properties for ReSOC. J. Electroceramics, 49(2), 85–93.
Abstract: In this work, we prepared La1 – xSrxGa1-yMgyO3 (LSGM) by the fast combustion method and assessed the electrical properties with respect to the composition and sintering temperature (1200, 1300, and 1400 degrees C by 6 h) as an electrolyte material for the reversible solid oxide cells (ReSOCs). For the preparation of samples, two different fuels, such as tartaric acid (TA) and citric acid (CA), with corresponding nitrate salts as precursors, were adopted for the fast combustion method (at 500 degrees C for 10 min). From the X-ray diffractograms, two main phases corresponding to LSGM orthorhombic (space group Imma) and LSGM-cubic (space group Pm-3 m) were identified. From the literature, both structures are reported as high oxygen ion conductive species, but normally they are not reported to appear together. Additionally, in some cases, an isolating (secondary) phase of LaSrGaO4 in a low concentration < 1.98% was observed. The scanning electron microscopy (SEM) studies on samples sintered at 1200 and 1300 degrees C revealed the smaller grain size and irregular morphology. The SEM micrographs depicted a well-defined superficial morphology with less porosity for the samples sintered at 1400 degrees C. For comparative analysis, the conductivity (S.cm(- 1)) was measured at varying temperatures (300-800 degrees C) for the samples sintered at 1300 and 1400 degrees C. Because of the large number of insulating phases produced by the incomplete sintering process, the samples sintered at 1300 degrees C had lower conductivities. A higher conductivity of 0.125 S.cm(- 1) was observed for La0.80Sr0.20Ga0.80Mg0.20O3 (LSGM), which was obtained using the citric acid (sintered at 1400 degrees C), which is in the range of earlier reported similar studies. The observed variation in the conductivity with respect to different phases of LSGM, the influence of the secondary phase, and the wt% of the constituents of LSGM are discussed.
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Sepúlveda, E., Sanhueza, F., Cobo, R., Jiménez, J., & Mangalaraja, R. V. (2024). Relationship among the powder mass, press charge, and final properties of an LSGM electrolyte for solid oxide cells. MRS Adv., Early Access.
Abstract: In this work, La0.85Sr0.15Ga0.85Mg0.15O3-delta (LSGM) was prepared as an electrolyte for solid oxide cell (SOC) applications. A fast combustion method was used, starting with nitrate salts and citric acid as fuel. Different parameters, such as mass and pressing load, in the pre-sintering step were used to obtain a highly ionic conductive material at intermediate temperatures. The aim is to find optimal processing conditions for energy savings. SEM analysis showed similar grain sizes and distributions for all samples. The XRD spectra showed two main phases corresponding to LSGM orthorhombic (space group Imma) and LSGM cubic (space group Pm-3m). LaSrGaO4 appeared in lighter samples. The EIS revealed that heavier samples present high conductivity, showing a clear relationship between conductivity, sample mass (during the pre-sintering step), and the LSGM phase amount. The effect of pressure was less evident. The highest conductivity was 0.013 and 0.063 S cm-1 at 600 and 800 degrees C, respectively.
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